The invention relates to compounds for targeting biological molecules and methods of making and using the compounds. Conventionally developed pharmaceutical drugs and biological effector molecules are often of limited use in therapy because of high toxicity. Various approaches have been used over the years to improve the therapeutic index of such drugs or effectors. One approach has been to couple a drug or effector to a ligand targeting agent such as an antibody. In this case, the antibody is used to change the distribution of drug or effector such that more of it can localize where it is most needed in vivo. Improved targeting of small molecular weight drugs or effectors has been achieved by complexing the drug or effector with a large molecular weight compound. For example, European Patent EP 217577 discloses that increased half life and targeting by an agent is achieved by forming complexes in vivo between hapten-modified agents and anti-hapten antibodies. Similarly, International Patent Application Publication WO 98/22141 discloses conjugates of therapeutic agents and haptens. The conjugates are administered to a subject and circulate in the blood stream of the subject. Circulating conjugates are recognized and bound by existing antibodies in the subject. Also, Shokat and Schultz (J. Am. Chem. Soc., 1991, 113:1862-1864) have disclosed a process for redirecting the immune response using a process referred to as ligand-mediated immunogenicity. According to this teaching, an invariant antigen is complexed with a specific ligand and administered to a subject. The complexed invariant antigen then binds naturally occurring antibodies present in the subject.